Document DE 10 2009 047 338 describes such an ammonia generating device including a reservoir separated into two portions to form a first central reservoir connected to the exhaust line of an automobile vehicle by controlled means for releasing the ammonia, here a metering valve, and a second reservoir. The first central reservoir has a size clearly smaller than that of the second reservoir. Each reservoir includes a different ammonia storage element, each element allowing release of the reducing agent following a desorption reaction. The first central reservoir is completely positioned inside the second reservoir and is connected to the latter through a switching valve, such as an anti-return valve.
Further, a heat generating element is positioned inside the first central reservoir.
The first central reservoir and the second reservoir are thermally connected to each other, so that when the heat generating element is activated, heat is also imparted to the second reservoir.
This ammonia generating device has the goal of allowing sufficient supply of reducing agent, regardless of the operating state of the vehicle, while limiting the energy required for releasing the reducing agent contained in the storage elements present in the first central reservoir and the second reservoir respectively.
Such an ammonia generating device is, however, complex to apply and may have uncertain operation notably when the heat produced by the heat generating element is insufficient for allowing the desorption reaction in the second reservoir, for example, when the vehicle covers a low mileage and when the duration for powering up the heat generating element is insufficient.